New dTALE system for the co-expression of multiple genes in rice.
The temporally and spatially targeted co-expression of multiple transgenes in plants often fails due to the limited availability of promoter sequences that are active only in specific tissue types and/or at specific developmental stages. IPB scientists, as part of an international expert team, have developed two different expression systems for use in rice based on designed transcription activator-like effectors (dTALES) and the corresponding synthetic TALE-activated promoters (STAPs). The systems allow the targeted activation of multiple transgenes, with the starting point of the expression chain always being a single promoter that drives the expression of the dTAL effector, which in turn activates different STAPs and thus the transcription of the downstream transgenes. The scientists tested the suitability of the dTALE and STAP sequences using the expression of different reporter genes in stable transgenic rice lines. They were able to show clear correlations between sequence identities of dTALE and STAPS and the corresponding transcript levels. The transcriptional activation system does not yet work quite perfectly: dTALE expression of the transgenes also led to off-target activations of plant-specific genes, but to a much lesser extent than with conventional transformation methods. Therefore, the scientists consider the dTALE-STAP system a powerful approach to fine-tune the expression of multiple transgenes.
The work was carried out as part of the C4 Rice Project, in which researchers from seven prestigious research institutions in England, Australia, Taiwan, Germany and America are collaborating to establish new technologies for developing high-yielding rice varieties. The community's ambitious goal is to increase the efficiency of photosynthesis in the C3 plant rice by integrating the genes for C4 photosynthesis, or parts of them. C4 species such as corn, sorghum and sugarcane have better carbon assimilation and higher temperature tolerance in hot and dry climates than C3 plants, which, like wheat, rye, barley and oat, are grown successfully in temperate climates. The C4 Rice Project is among the great scientific challenges of the 21st century. IPB has been a member of the project since 2019.
Original Publication:
Florence Danila, Tom Schreiber, Maria Ermakova, Lei Hua, Daniela Vlad, Shuen-Fang Lo, Yi-Shih Chen, Julia Lambret Frotte, Anna S. Hermanns, Benedikt Athmer, Susanne von Caemmerer, Su-May Yu, Julian M. Hibberd, Alain Tissier, Robert T. Furbank, Steven Kelly & Jane A. Langdale. A single promoter-TALE system for tissue-specific and tuneable expression of multiple genes in rice. Plant Biotechnol J 2022 doi: 10.1111/pbi.13864.
